Around the same time that Dr. Keys was presenting his research, another scientist, Dr. John Yudkin, came to a different conclusion – that it was excessive consumption of processed sugars that was driving the increase in coronary heart disease.

And for the next 60 years, both hypotheses have been defended with a succession of studies that:

Unfortunately for us “normal people” who are looking to ways to live longer & better, this kind of science is pretty darn sketchy. Here’s why:

If you have pizza for dinner tonight, Dr. Keys would tell you that the saturated fat found in the cheese & pepperoni is bad for your heart. Conversely, Dr. Yudkin would blame the processed flour used to make the pizza crust.

So…who’s right?

If we rely on observational studies to answer this question, we will never come to a consensus. People don’t eat individual nutritional components…we eat FOOD. We eat meals in which we mix carbs and fats and proteins together.

Observational studies do nothing to separate those components and because of this…this kind of study is next to useless.

Luckily for us health-nerds, in the past fifty years, researchers have added to the observational studies with a giant body of research employing basic science, epidemiology and clinical trial data to provide us with a clearer picture of the relationship between nutrition and CHD risk, CHD events and CHD mortality.

Saturated fat can raise levels of total serum cholesterol (TC) but TC is only modestly associated with coronary heart disease (CHD) and that some types of saturated fat are actually protective against CHD.

Conversely, when saturated fats are replaced with refined carbohydrates, and specifically with added sugars, we see increases in low-density lipoproteins (LDL), increases in triglycerides and decreases in high-density lipoproteins (HDL) that are shown to increase your odds of CHD.

Does this mean that all sugars / carbs are bad?

NO, because while the body of research indicates that “a diet high in added sugars has been found to cause a 3-fold increased risk of death due to cardiovascular disease”, that doesn’t mean that all sugar/carbs are created alike.

Like some saturated fats are cardio-protective, we know that natural sugars found in whole fruits, grains and vegetables are not causing coronary heart disease.

It’s the processed fructose-containing sugars like sucrose and high-fructose corn syrup found in highly processed junk foods that are the problem.